Mirror drive device capable of high-speed driving and image pickup apparatus

ABSTRACT

A mirror drive device capable of achieving lower torque and higher speed in mirror driving without necessitating reversing of an urging direction of an urging member during the mirror driving and improve durability thereof at the same time. A main mirror holder holding a main mirror is movable between a mirror-down position is a photographing optical path and a mirror-up position retracted from the photographing optical path. A sub mirror holder holding a sub mirror and rotatably attached to the main mirror bolder is movable between a mirror-down position and a mirror-up position. The sub mirror holder is moved by a driving member from the mirror-down position to the mirror-up position, whereby the main mirror holder is moved from the mirror-down position to the mirror-up position.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a mirror drive device equipped with amechanism for high-speed driving of a mirror unit provided in an imagepickup apparatus, such as a single-lens reflex camera, and an imagepickup apparatus equipped with the mirror drive device.

Description of the Related Art

In a quick return mirror mechanism e.g. of a single-lens reflex camera,a mirror unit provided with a main mirror and a sub mirror is moved athigh speed between a mirror-down position in which the mirror unitenters a photographing optical path and a mirror-up position in whichthe mirror unit is retracted from the photographing optical path. Eachof the mirrors of the mirror unit is brought into contact with a stopperformed in a mirror box, at the mirror-down position, thereby being heldin a predetermined stop position, to guide an object light flux havingpassed through a photographic optical system of the lens unit to aviewfinder optical system and a focus detection unit.

Conventionally, there has been proposed a mirror drive device thatdrives the mirror unit between the mirror-down position and themirror-up position by transmitting a driving force to the main mirror ofthe mirror unit and causing the sub mirror to follow the main mirrorusing a toggle spring and a reversing cam. In the proposed mirror drivedevice, the toggle spring urges the sub mirror in a mirror-downdirection when the mirror unit is in the mirror-down position, and urgesthe same in a mirror-up direction when the mirror unit is in themirror-up position (see Japanese Patent Laid-Open Publication No.2011-85762).

According to the mirror drive device proposed in Japanese PatentLaid-Open Publication No. 2011-85762, in order to achieve high turningspeed of the mirror unit, it is required to increase the spring force ofthe toggle spring for urging the sub mirror. However, if the springforce of the toggle spring is increased, the mirror unit reaches themirror-down position or the mirror-up position at the increased turningspeed of the sub mirror and the main mirror, which causes a large bounceof each mirror and an increase in mirror driving sound.

Further, according to the mirror drive device proposed in JapanesePatent Laid-Open Publication No. 2011-85762, a large torque is requiredfor reversing the urging direction of the toggle spring for urging thesub mirror following the main mirror between the mirror- up position andthe mirror-down position. For this reason, there is a limit toincreasing mirror driving speed. Further, a large load is applied to thereversing cam that reverses the direction of urging the sub mirror, andhence there is concern about the durability of the mirror drive device.

SUMMARY OF THE INVENTION

The present invention provides a mirror drive device and an image pickupapparatus which make it possible to achieve lowered torque and increasedspeed in mirror driving without requiring reversing of the urgingdirection of an urging member during the mirror driving, and improve thedurability of the mirror drive device at the same time.

Further, the invention provides a mirror drive device and an imagepickup apparatus which are capable of not only driving a mirror at highspeed, but also reducing the magnitude of mirror bounce or mirrordriving sound during the mirror driving.

In a first aspect of the invention, there is provided a mirror drivedevice comprising a first mirror holder that holds a first mirror and isconfigured to be movable between a first position in a photographingoptical path and a second position retracted from the photographingoptical path, a second mirror holder that holds a second mirror in astate rotatably attached to the first mirror holder and is configured tobe movable between a third position in the photographing optical pathand a fourth position retracted from the photographing optical path, amotor, and a driving member configured to be driven by the motor tothereby move the second mirror holder between the third position and thefourth position, wherein the driving member moves the second mirrorholder from the third position to the fourth position, whereby the firstmirror holder is moved from the first position to the second position.

In a second aspect of the invention, there is provided a mirror drivedevice comprising a first mirror holder that holds a first mirror and isconfigured to be movable between a first position in a photographingoptical path and a second position retracted from the photographingoptical path, a second mirror holder that holds a second mirror in astate rotatably attached to the first mirror holder and is configured tobe movable between a third position in the photographing optical pathand a fourth position retracted from the photographing optical path, amotor, a driving member configured to be driven by the motor to therebymove the second mirror holder between the third position and the fourthposition, and a control unit configured to control driving of the motor,wherein when the second mirror holder is moved from the third positionto the fourth position by the driving member, the first mirror holder ispositioned in the first position without being moved until the secondmirror holder is brought into contact therewith, and after the secondmirror holder is brought into contact therewith, the first mirror holderis moved to the second position together with the second mirror holder,and wherein the control unit controls the motor to reduce speed thereofto thereby reduce speed of the second mirror holder when the secondmirror holder reaches a predetermined first setting position before thesecond mirror holder is brought into contact with the first mirrorholder, controls the motor to increase the speed thereof to therebyincrease the speed of the second mirror holder after the second mirrorholder is brought into contact with the first mirror holder, andcontrols the motor to reduce the speed thereof to thereby reduce thespeed of the second mirror holder when the first mirror holder is movedtoward the second position together with the second mirror holder andreaches a predetermined second setting position advance before reachingthe second position.

In a third aspect of the invention, there is provided a mirror drivedevice comprising a first mirror holder that holds a first mirror and isconfigured to be movable between a first position in a photographingoptical path and a second position retracted from the photographingoptical path, a second mirror holder that holds a second mirror in astate rotatable attached to the first mirror holder and is configured tobe movable between a third position in the photographing optical pathand a fourth position retracted from the photographing optical path, amotor, a driving member configured to be driven by the motor to therebymove the second mirror holder between the third position and the fourthposition, and a control unit configured to control driving of the motor,wherein when the second mirror holder is moved from the fourth positionto the third position by the driving member, the first mirror holder ismoved from the second position toward the first position together withthe second mirror holder, and reaches the first position, and after thefirst mirror holder reaches the first position, the second mirror holderis moved toward the third position, and reaches the third position, andwherein the control unit controls the motor to reduce speed thereof tothereby reduce the speed of the second mirror holder when the firstmirror holder is moved from the second position toward the firstposition together with the second mirror holder and reaches apredetermined first setting position before reaching the first position,controls the motor to increase the speed thereof to thereby increase thespeed of the second mirror holder after the first mirror holder reachesthe first position, and controls the motor to reduce the speed thereofto thereby reduce the speed of the second mirror holder when the secondmirror holder reaches a predetermined second setting position beforereaching the third position.

In a fourth aspect of the invention, there is provided an image pickupapparatus comprising a first mirror holder that holds a first mirror andis configured to be movable between a first position in a photographingoptical path and a second position retracted from the photographingoptical path, a second mirror holder that holds a second mirror in astate rotatably attached to the first mirror holder and is configured tobe movable between a third position in the photographing optical pathand a fourth position retracted from the photographing optical path, amotor, and a driving member configured to be driven by the motor tothereby move the second mirror holder between the third position and thefourth position, wherein the driving member moves the second mirrorholder from the third position to the fourth position, whereby the firstmirror holder is moved from the first position to the second position.

In a fifth aspect of the invention, there is provided an image pickupapparatus comprising a first mirror holder that holds a first mirror andis configured to be movable between a first position in a photographingoptical path and a second position retracted from the photographingoptical path, a second mirror holder that holds a second mirror in astate rotatably attached to the first mirror holder and is configured tobe movable between a third position in the photographing optical pathand a fourth position retracted from the photographing optical path, amotor, a driving member configured to be driven by the motor to therebymove the second mirror holder between the third position and the fourthposition, and a control unit configured to control driving of the motor,wherein when the second mirror holder is moved from the third positionto the fourth position by the driving member, the first mirror holder ispositioned in the first position without being moved until the secondmirror holder is brought into contact therewith, and after the secondmirror holder is brought into contact therewith, the first mirror holderis moved to the second position together with the second mirror holder,and wherein the control unit controls the motor to reduce speed thereofto thereby reduce speed of the second mirror holder when the secondmirror holder reaches a predetermined first setting position before thesecond mirror holder is brought into contact with the first mirrorholder, controls the motor to increase the speed thereof to therebyincrease the speed of the second mirror holder after the second mirrorholder is brought into contact with the first mirror holder, andcontrols the motor to reduce the speed thereof to thereby reduce thespeed of the second mirror holder when the first mirror holder is movedtoward the second position together with the second mirror holder andreaches a predetermined second setting position before reaching thesecond position.

In a sixth aspect of the invention, there is provided an image pickupapparatus comprising a first mirror holder that holds a first mirror andis configured to be movable between a first position in a photographingoptical path and a second position retracted from the photographingoptical path, a second mirror holder that holds a second mirror in astate rotatably attached to the first mirror holder and is configured tobe movable between a third position in the photographing optical pathand a fourth position retracted from the photographing optical path, amotor, a driving member configured to be driven by the motor to therebymove the second mirror holder between the third position and the fourthposition, and a control unit configured to control driving of the motor,wherein when the second mirror holder is moved from the fourth positionto the third position by the driving member, the first mirror holder ismoved from the second position toward the first position together withthe second mirror holder, and reaches the first position, and after thefirst mirror holder reaches the first position, the second mirror holderis moved toward the third position, and reaches the third position, andwherein the control unit controls the motor to reduce speed thereof tothereby reduce the speed of the second mirror holder when the firstmirror holder is moved from the second position toward the firstposition together with the second mirror holder and reaches apredetermined first setting position before reaching the first position,controls the motor to increase the speed thereof to thereby increase thespeed of the second mirror holder after the first mirror holder reachesthe first position, and controls the motor to reduce the speed thereofto thereby reduce the speed of the second mirror holder when the secondmirror holder reaches a predetermined second setting position beforereaching the third position.

According to the first and fourth aspects of the invention, it ispossible to provide a mirror drive device and an image pickup apparatuswhich make it possible to achieve lowered torque and increased speed inmirror driving without requiring reversing of the urging direction ofthe urging member during the mirror driving and improve durabilitythereof at the same time.

According to the second, third, fifth and sixth aspects of theinvention, it is possible to provide a mirror drive device and an imagepickup apparatus which are capable of not only driving a mirror at highspeed, but also reducing the magnitude of bounce of the mirror or mirrordriving sound during the mirror driving.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the system configuration of a digitalsingle-lens reflex camera which is an image pickup apparatus equippedwith a mirror drive device according to an embodiment of the presentinvention.

FIG. 2A is a schematic side cross-sectional view of the digitalsingle-lens reflex camera in a mirror-down position.

FIG. 2B is a schematic side cross-sectional view of the digitalsingle-lens reflex camera in a mirror-up position.

FIG. 3 is an exploded perspective view of a mirror drive unit.

FIG. 4 is an exploded perspective view of a mirror charge unit.

FIG. 5A is a front view of the mirror drive unit as viewed from anoptical axis direction.

FIG. 5B is a right side view of the mirror drive unit shown in FIG. 5A.

FIG. 6 is a view of the mirror drive unit shown in FIG. 5B, with itsmotor and gear base removed therefrom.

FIG. 7 is a view useful in explaining the relationship between a mirrorunit and the mirror charge unit.

FIGS. 8A to BE are views useful in explaining states of components ofthe mirror drive unit when the mirror unit is in the mirror-downposition.

FIGS. 9A to 9E are views useful in explaining states of the componentsof the mirror drive unit immediately before a cam gear and a mirrordrive gear are brought into mesh with each other immediately after themirror drive unit starts mirror-up driving.

FIGS. 10A to 10E are views useful in explaining states of the componentsof the mirror drive unit immediately before the mirror unit starts amirror-up operation.

FIGS. 11A to 11E are views useful in explaining states of the componentsof the mirror drive unit when a sub mirror holder is performing itsmirror-up operation.

FIGS. 12A to 12E are views useful in explaining states of the componentsof the mirror drive unit when a main mirror holder starts its mirror-upoperation.

FIGS. 13A to 13E are views useful in explaining states of the componentsof the mirror drive unit immediately before the mirror unit completesthe mirror-up operation.

FIGS. 14A to 14E are views useful in explaining states of the componentsof the mirror drive unit when the mirror unit is in the mirror-upposition.

FIGS. 15A to 15E are views useful in explaining states of the componentsof the mirror drive unit immediately after the mirror drive unit startsmirror-down driving.

FIGS. 16A to 16E are views useful in explaining states of the componentsof the mirror drive unit immediately before the mirror unit starts amirror-down operation.

FIGS. 17A to 17E are views useful in explaining states of the componentsof the mirror drive unit when the main mirror holder reaches itsmirror-down position.

FIGS. 18A to 18E are views useful in explaining states of the componentsof the mirror drive unit immediately before the sub mirror holderreaches its mirror-down position.

FIG. 19A is a graph showing the relationship between the position of themirror unit and time during the mirror-up operation.

FIG. 19B is a graph showing the relationship between the position of themirror unit and time during the mirror-down operation.

FIG. 20A is a flowchart of a mirror drive control process performedduring the mirror-up operation of the mirror unit.

FIG. 20B is a flowchart of a mirror drive control process performedduring the mirror-down operation of the mirror unit.

DESCRIPTION OF THE EMBODIMENTS

The present invention will now be described in detail below withreference to the accompanying drawings showing embodiments thereof.

FIG. 1 is a block diagram of the system configuration of a digitalsingle-lens reflex camera which is an image pickup apparatus equippedwith a mirror drive device according to an embodiment of the presentinvention

Referring to FIG. 1, in the digital single-lens reflex camera(hereinafter referred to as the camera) according to the presentembodiment, an interchangeable lens unit 210 is mounted on a camera body1 via a mount contact portion 21 in a removable manner.

First, a description will be given of the camera body 1. In FIG. 1, amicrocomputer 100 (hereinafter referred to as the MPU 100) controls theoverall operation of the camera. An EEPROM 100 a incorporated in the MPG100 stores time information of a time measurement circuit 109, controlprograms, and other information items. To the MPU 100, there areconnected a mirror drive circuit 101, a focus detection circuit 102, ashutter drive circuit 103, a video signal processing circuit 104, aswitch sensing circuit 105, and a photometric circuit 24 of a viewfinderoptical system 4. Further, to the MPU 100, there are connected a displaydrive circuit 107, a battery check circuit 108, the time measurementcircuit 109, a power supply circuit 110, and a piezoelectric elementdrive circuit 111, and these circuits are driven by the control of theMPU 100.

A mirror unit 500 includes a main mirror 501 formed by a half mirror,and a sub mirror 503, which are moved to a position where they retractfrom a photographing optical path (mirror-up position) duringphotographing, and are moved to a position where they enter thephotographing optical path (mirror-down position) during finderobservation.

When the mirror unit 500 is in the mirror-down position, the main mirror501 reflects an object light flux having passed through a photographiclens 200 as a component of a photographic optical system of the lensunit 210, thereby guiding the same to the viewfinder optical system 4,and also causes part of the object light flux to transmit therethrough,thereby guiding the same to the sub mirror 503. The sub mirror 503reflects the object light flux transmitted through the main mirror 501,thereby guiding the same to a focus detection unit 31. Further, when themirror unit 500 is in the mirror-up position, the object light fluxhaving passed through the photographic lens 200 is guided to an imagepickup device 33.

The mirror drive circuit 101 controls driving of a motor 601 (see FIG.3) for rotating the mirror unit 500 between the mirror-up position (seeFIG. 2B) and the mirror-down position (see FIG. 2A), and detects aposition of the mirror unit 500.

The focus detection unit 31 is formed by a field lens disposed in thevicinity of an imaging surface, not shown, a reflection mirror, asecondary imaging lens, a diaphragm, a line sensor formed by a pluralityof CCD sensors, and so forth. A signal output from the focus detectionunit 31 is supplied to the focus detection circuit 102, and is sent tothe MPU 100 after being converted to an object image signal. The MPU 100performs focus detection calculation by a phase difference detectionmethod based on the supplied object image signal. Then, the MPU 100calculates a defocus amount and a defocus direction, and controls a lenscontrol circuit 201 and an AF drive circuit 202 of the lens unit 210 todrive a focus lens of the photographic lens 200 to an in-focus positionbased on a result of the calculation.

A pentaprism 22 converts the object light flux reflected by the mainmirror 501 in the mirror-down position to an erect normal image toreflect the converted image, whereby a user can view the converted erectnormal image, as an object image, from a finder eyepiece window 18 viathe viewfinder optical system 4. Further, the pentaprism 22 also guidespart of the object light flux to a photometry sensor 23, and thephotometric circuit 24 converts photometric results output from thephotometry sensor 23 to luminance signals of respective areas on anobservation surface, and outputs the luminance signals to the MPU 100.The MPU 100 calculates an exposure value based on the luminance signalsoutput from the photometric circuit 24.

A focal plane shutter 106 blocks an object light flux guided to theimage pickup device 33 during finder observation, and duringphotographing, operates to obtain a desired exposure time based on atime difference between traveling of a front curtain, not shown, andtraveling of a rear curtain, not shown, in response to a release signalinput by the user. The focal plane shutter 106 is controlled by theshutter drive circuit 103 in response to a command from the MPU 100.

An image pickup device unit 114 is comprised of the image pickup device33, a laminate-type piezoelectric element 112, and an optical low-passfilter 113. The image pickup device 33 is implemented e.g. by a CCDsensor, a CMOS sensor, or a CID sensor. A clamp/CDS (correlated doublesampling) circuit 34 performs basic analog processing before A/Dconversion, and is also capable of changing a clamp level. An AGC(automatic gain controller) 35 performs basic analog processing beforeAID conversion, and is also capable of changing an AGC basic level. Ananalog-to-digital converter 36 converts an analog signal output from theimage pickup device 33 to a digital signal.

An infrared ray cut filter 32 is formed into a substantially rectangularshape, and cuts unnecessary infrared light of an object light flux to beguided to the image pickup device 33. The infrared ray cut filter 32 hasa surface covered by a conductive material in order to prevent foreignmatter from sticking thereto. The optical low-pass filter 113 is formedby laminating and affixing a plurality of birefringent plates and phaseplates, which are made of quartz, to each other, and further affixing aninfrared ray cut filter to the resulting laminate. The laminate-typepiezoelectric element 112 is excited by the piezoelectric element drivecircuit 111 having received a command from the MPU 100, and vibrationthereof is transmitted to the optical low-pass filter 113.

The video signal processing circuit 104 performs general imageprocessing by hardware, such as gamma/knee processing, filteringprocessing, and information synthesis processing for monitor display, ondigital image data. Color image data for monitor display, output fromthe video signal processing circuit 104 is displayed on a color liquidcrystal monitor 19 via a monitor drive circuit 115.

Further, the video signal processing circuit 104 is also capable ofstoring image data in a buffer memory 37 via a memory controller 38according to an instruction from the MPU 100. Further, the video signalprocessing circuit 104 has a function of performing image datacompression processing, such as JPEG compression. Further, in a casewhere images are continuously photographed e.g. by continuousphotographing, the video signal processing circuit 104 is also capableof temporarily storing image data in the buffer memory 37, andsequentially reading out unprocessed image data via the memorycontroller 38. This enables the video signal processing circuit 104 tosequentially perform image processing and compression processing on theunprocessed image data regardless of a rate at which image data isoutput from the A/D converter 36.

The memory controller 38 has a function of storing image data outputfrom an external interface 40, such as a USB output connector, in amemory 39, and a function of outputting image data stored in the memory39 to the external interface 40. Note that as the memory 39, forexample, a flash memory is used which can be mounted and removed to andfrom the camera body 1.

A release switch (SW1) 7 a is turned on e.g. by an operation ofhalf-pressing a release button, not shown, and sends an operation signalfor starting photographing preparation to the MPU 100 via the switchsensing circuit 105. A release switch (SW2) 7 b is turned on e.g. by anoperation of fully pressing the release button, and sends an operationsignal for starting photographing to the MPU 100 via the switch sensingcircuit 105. Further, the switch sensing circuit 105 sends operationsignals to the MPU 100 according to the respective operating states of amain operation dial 8, a sub operation dial 20, a photographingmode-setting dial 14, a main switch 43, and a cleaning instructionmember 44.

The display drive circuit 107 drives an external display device 9 and anin-finder display device 41 according to instructions from the MPU 100.The battery check circuit 108 performs battery check for a predeterminedtime period according to an instruction from the MPU 100, and sends aresult of the check to the MPU 100. A power supply section 42 suppliesnecessary power to the components of the camera according to aninstruction provided from the MPU 100 via the power supply circuit 110.The time measurement circuit 109 measures a time period elapsed afterthe main switch 43 is turned off until the main switch 43 is turned onnext, and sends a result of the measurement to the MPU 100 in responseto a command from the MPU 100.

Next, a description will be given of the lens unit 210. The lens unit210 includes the lens control circuit 201, and the lens control circuit201 performs communication with the MPU 100 of the camera body 1 via themount contact portion 21. The mount contact portion 21 also has afunction of sending a signal to the MPU 100 when the lens unit 210 isconnected to the camera body 1.

The lens control circuit 201 performs communication with the MPU 100 byusing this function, and drives the photographic lens 200 and thediaphragm, denoted by reference numeral 204, via the AF drive circuit202 and a diaphragm drive circuit 203. Although FIG. 1 shows onephotographic lens 200 for convenience of explanation, the photographiclens 200 is actually formed by a lens group including a plurality oflenses.

The AF drive circuit 202 is comprised of e.g. a stepping motor, andchanges the position of the focus lens of the photographic lens 200 in adirection of an optical axis under the control of the lens controlcircuit 201 to thereby perform the focusing operation. The diaphragmdrive circuit 203 is comprised of e.g. an automatic iris, and changesthe opening diameter of the diaphragm 204 under the control of the lenscontrol circuit 201 to thereby obtain an optical aperture value.

FIG. 2A is a schematic side cross-sectional view of the camera when themirror unit 500 is in the mirror-down position. FIG. 2B is a schematicside cross-sectional view of the camera when the mirror unit 500 is inthe mirror-up position.

As shown in FIGS. 2A and 2B, the main mirror 501 of the mirror unit 500is held by a main mirror holder 502, and the sub mirror 503 is held by asub mirror holder 504. Further, the main mirror holder 502 is rotatablysupported with respect to a mirror box 400 (see FIG. 3), and the submirror holder 504 is rotatably supported with respect to the main mirrorholder 502. The mirror unit 500 is driven by a mirror drive unit 1000,and is turned between the mirror-down position shown in FIG. 2A and themirror-up position shown in FIG. 2B.

Here, the main mirror 501, the sub mirror 503, the main mirror holder502, and the sub mirror holder 504 correspond to respective examples ofa first mirror, a second mirror, a first mirror holder, and a secondmirror holder. Further, the mirror-down position and the mirror-upposition of the main mirror holder 502 correspond to respective examplesof a first position and a second position. Further, the mirror-downposition and the mirror-up position of the sub mirror holder 504correspond to respective examples of a third position and a fourthposition.

In the mirror-down position shown in FIG. 2A, the mirror unit 500 entersthe photographing optical path, an object light flux having passedthrough the photographic lens 200 is reflected by the main mirror 501,and part of the object light flux is transmitted through the main mirror501 and is reflected by the sub mirror 503. The object light fluxreflected by the main mirror 501 is guided to the pentaprism 22 of theviewfinder optical system 4, and the object light flux reflected by thesub mirror 503 is guided to the focus detection unit 31.

Further, in the mirror-up position shown in FIG. 2B, the mirror unit 500is retracted from the photographing optical path, and an object lightflux having passed through the photographic lens 200 is guided to theimage pickup device 33 to form an image, which is photoelectricallyconverted.

FIG. 3 an exploded perspective view of the mirror drive unit 1000. Asshown in FIG. 3, the mirror drive unit 1000 includes the mirror box 400,the mirror unit 500, and a mirror charge unit 600.

The main mirror holder 502 of the mirror unit 500 is formed withrotational shafts 502 a, and the rotational shafts 502 a are rotatablysupported with respect to the mirror box 400. Further, the main mirrorholder 502 is formed with a shaft portion 502 c having a semicircularcross section, and a first contact portion 502 b. When the mirror unit500 is in the mirror-down position, the shaft portion 502 c of the mainmirror holder 502 is urged in a mirror-down direction by the other endof a spring 607 having one end hooked on a spring urging portion 604 d,and the first contact portion 502 b is brought into contact with apositioning shaft 507. The positioning shaft 507 is formed e.g. by aneccentric pin, and by rotating the positioning shaft 507, it is possibleto adjust the mirror-down position or the main mirror holder 502. Thespring 607 corresponds to an example of an urging member.

The sub mirror holder 504 is formed with support holes 504 a, and isrotatably supported on rotational shaft portions 502 d of the mainmirror holder 502 by having the support holes 504 a fitted thereon. Thismake the sub mirror holder 504 rotatable with respect to the main mirrorholder 502 about the rotational shaft portions 502 d.

Further, the sub mirror holder 504 is formed with a drive shaft portion504 c and a first contact portion 504 b. When the mirror unit 500 is inthe mirror-down position, the drive shaft portion 504 c of the submirror holder 504 is urged by a spring 608 in the mirror-down direction,and the first contact portion 504 b is brought into contact with apositioning shaft 508. The positioning shaft 508 is formed e.g. by aneccentric pin, and by rotating the positioning shaft 508, it is possibleto adjust the mirror-down position of the sub mirror holder 504.

The mirror box 400 is provided with a stopper 505 with which a front endof the main mirror holder 502 rotated to the mirror-up position isbrought into contact. The stopper 505 is formed of an elastic memberwhich can absorb impact applied when the main mirror holder 502 isbrought into contact with the stopper 505. Further, on a rear side ofthe mirror box 400, there is disposed a shaft retaining plate 506 forretaining the rotational shafts 502 a of the main mirror holder 502. Byattaching the shaft retaining plate 506 to the mirror box 400, the mainmirror holder 502 is mounted on the mirror box 400 in a manner rotatablewith respect thereto without coming off.

The mirror charge unit 600 is mounted on a right side of the mirror box400, as viewed from the direction of the optical axis O. The mirrorcharge unit 600 includes the motor 601, a cam gear 603, a mirror drivelever unit 700, photo-interrupters 609 and 610, and a gear base 611. Themotor 601 is supported on the gear base 611, and the gear base 611 ismounted on the right side of the mirror box 400, as viewed from thedirection of the optical axis O, with screws 611 s.

FIG. 4 is an exploded perspective view of the mirror charge unit 600. Asshown in FIG. 4, the cam gear 603 is rotatably supported on a firstshaft portion 611 a of the gear base 611 by having the first shaftportion 611 a fitted in a support hole 603 a thereof, which is thecenter of rotation. The mirror drive lever unit 700 includes a mirrordrive lever 604, a mirror drive gear 605, and a spring 606, and thesprings 607 and 608.

The mirror drive lever 604 has a support hole 604 a, which is the centerof rotation, and is rotatably supported on a second shaft portion 611 bformed on the gear base 611 by having the second shaft portion 611 bfitted in the support hole 604 a. The mirror drive gear 605 also has asupport hole 605 a, which is the center of rotation, and is rotatablysupported on the second shaft portion 611 b formed on the gear base 611by having the second shaft portion 611 b fitted in the support hole 605a. That is, the mirror drive lever 604 and the mirror drive gear 605 arerotatably mounted with respect to the gear base 611 coaxially with eachother.

The mirror drive lever 604 is attached to the mirror drive gear 605 viathe spring 606. More specifically, one end 606 a of the spring 606 ishooked on a spring urging portion 604 f which is part of the mirrordrive lever 604, and the other end 606 b of the spring 606 is hooked ona spring urging portion 605 g which is part of the mirror drive gear605.

In this state, the spring 606 is urged in a direction in which the oneend 606 a and the other end 606 b thereof sandwich the spring urgingportion 604 f and the spring urging portion 605 g. This enables themirror drive lever 604 to rotate substantially in unison with the mirrordrive gear 605. Further, the spring 607 for urging the main mirrorholder 502 in the mirror-down direction, and the spring 608 for urgingthe sub mirror holder 504 in the mirror-down direction are held on themirror drive lever 604.

The motor 601 formed e.g. by a stepping motor is fixed to the gear base611, and has a pinion 602 fitted on an output shaft thereof. The mirrordrive circuit 101 counts the number of pulses supplied to the motor 601from the start of driving of the mirror unit 500, and this enables theMPU 100 to recognize the phase of the mirror unit 500 via the mirrordrive circuit 101.

When the cam gear 603 and the motor 601 are mounted on the gear base611, a first gear portion 603 b formed on the cam gear 603 and thepinion 602 of the motor 601 are meshed with each other. Further, whenthe mirror drive lever unit 700 is mounted on the gear base 611, asecond gear portion 603 c formed on the cam gear 603 and a gear portion605 b of the mirror drive gear 605 are meshed with each other.Therefore, a driving force of the motor 601 is transmitted to the mirrordrive lever unit 700 via the cam gear 603. Here, the cam gear 603, themirror drive lever 604, and the mirror drive gear 605 correspond to anexample of a driving member.

The photo-interrupters 609 and 610 are fixedly engaged with a firstlocking portion 611 c and a second locking portion 611 d, formed on thegear base 611, respectively. As the cam gear 603 is rotated, the statesof the photo-interrupters 609 and 610 are each changed by a lightshielding plate 603 f formed on the cam gear 603 between alight-receiving state and a non-light-receiving state. The MPU 100determines the phase of the mirror unit 500 via the mirror drive circuit101 based on the output signals from the photo-interrupters 609 and 610.

FIG. 5A is a front view of the mirror drive unit 1000 as viewed from theoptical axis direction, and FIG. 5B is a right side view of the mirrordrive unit 1000. As shown in FIG. 5B, the mirror charge unit 600 ismounted on one of the sides of the mirror box 400.

FIG. 6 is a view of the mirror drive unit 1000 shown in FIG. 5B, withthe motor 601 and the gear base 611 removed therefrom. In the stateshown in FIG. 6, the mirror unit 500 is in the mirror-down position.

FIG. 7 is a view useful in explaining the relationship between themirror unit 500 and the mirror charge unit 600. Note that FIG. 7 showsonly the mirror unit 500, the mirror drive lever 604, and the springs607 and 608, appearing in FIG. 6.

Referring to FIG. 7, the center of the rotational shaft 502 a of themain mirror holder 502 is set as A. Further, the center of the supporthole 504 a which is the center of rotation of the sub mirror holder 504in the mirror-down state is set as B, and the center of the support hole504 a which is the center of rotation of the sub mirror holder 504 inthe mirror-up state is set as C. Here, the center A of the rotationalshaft 502 a of the main mirror holder 502 corresponds to an example of afirst rotation center, and the centers B and C of rotation of the submirror holder 504 correspond to an example of a second rotation center.

At this time, as shown in FIG. 7, the center of the support hole 604 awhich is the center of rotation of the mirror drive lever 604 ispositioned radially inside a segment of a sector formed by connecting Band C with A in the center. This makes it possible to reduce changes indistance from the center of the support hole 604 a which is the centerof rotation of the mirror drive lever 604 to the drive shaft portion 504c of the sub mirror holder 504 during driving of the mirror unit 500.Therefore, it is possible to reduce load variation occurring duringdriving of the mirror unit 500.

Further, in the present embodiment, the center of the support hole 604 awhich is the center of rotation of the mirror drive lever 604 ispositioned radially inside the segment of the sector formed about A byconnecting B and C, and also in an area closer to B than to C. Withthis, although detailed description will be given hereinafter, a downlever portion 604 g (see FIG. 8E) of the mirror drive lever 604 passes aroute different from a rotation locus of the shaft portion 502 c of themain mirror holder 502 during the mirror-up operation of the mirror unit500.

Further, when the mirror-down operation of the mirror unit 500 isstarted, the down lever portion 604 g of the mirror drive lever 604 isbrought into contact with the shaft portion 502 c of the main mirrorholder 502, and is enabled to assist the mirror-down operation. Notethat even when the center of the support hole 604 a which is the centerof rotation of the mirror drive lever 604 is positioned radially outsidethe above-mentioned segment of the sector, the mirror-up/mirror-downoperation can be performed. The down lever portion 604 g corresponds toan example of an abutment portion.

Next, a description will be given of mirror-up driving and mirror-downdriving of the mirror unit 500, performed by the mirror drive unit 1000,with reference to FIGS. 8A to 8E. FIGS. 8A to 8E are views useful inexplaining states of components of the mirror drive unit 1000 when themirror unit 500 is in the mirror-down position.

FIG. 8A is a front view useful in explaining the states of thecomponents of the mirror drive unit 1000 when the mirror unit 500 is inthe mirror-down position. Note that in FIG. 8A, the mirror box 400, themotor 601, and the gear base 611 are omitted. FIG. 8B is a right sideview of FIG. 8A. FIG. 8B shows the relationship between the lightshielding plate 603 f of the cam gear 603 and the photo-interrupters 609and 610, when the mirror unit 500 is in the mirror-down position.

In the state shown in FIG. 8B, the photo-interrupter 609 is in thelight-receiving state, and the photo-interrupter 610 is in thenon-light-receiving state due to being shielded from light by the lightshielding plate 6031 of the cam gear 603. At this time, the MPU 100determines via the mirror drive circuit 101 that the mirror unit 500 isin the mirror-down state.

FIG. 8C is a cross-sectional view taken along c-c in FIG. 8A. FIG. 8Cshows the relationship between the second gear portion 603 c (in FIG.8C, the reference numeral 603 c denotes an area surrounding thecorresponding gear portion as a rectangle indicated by broken lines) ofthe cam gear 603 and the gear portion 605 b (in FIG. 8C, the referencenumeral 605 b denotes an area surrounding the corresponding gear portionas a rectangle indicated by broken lines; the same applies hereafter) ofthe mirror drive gear 605, when the mirror unit 500 is in themirror-down position. In the state shown in FIG. 8C, the second gearportion 603 c of the can; gear 603 and the gear portion 605 h of themirror drive gear 605 are not in mesh with each other.

FIG. 8D is a cross-sectional view taken along d-d in FIG. 8A. FIG. 8Dshows the relationship between a first cam portion 603 d and a secondcam portion 603 e of the cam gear 603, and a first follower portion 605c and a second follower portion 605 d of the mirror drive gear 605, whenthe mirror unit 500 is in the mirror-down position.

In the state shown in FIG. 8D, the first cam portion 603 d of the camgear 603 is in contact with the first follower portion 605 c of themirror drive gear 605. The first can portion 603 d of the cam gear 603has a circular arc cam shape concentric with part of the cam gear 603without a cam lift. Therefore, even when the cam gear 603 is rotated tosome degree in a cam area of the first cam portion 603 d in this state,rotation is not transmitted to the mirror drive gear 605, so that themirror drive gear 605 is not rotated.

Further, in this state, when the mirror drive gear 605 is brought intocontact with the cam gear 603, in a state urged in the mirror-updirection (clockwise direction as viewed in FIG. 8D), the mirror drivegear 605 is brought into contact with the cam gear 603 such that theurging force acts in a direction substantially toward the center ofrotation of the cam gear 603. Therefore, in the state shown in FIG. 8D,unless the cam gear 603 is rotated, the mirror drive gear 605 restrictedfrom rotating in the mirror-up direction.

FIG. 8E is a cross-sectional view taken along e-e in FIG. 8A. FIG. 8Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608), whenthe mirror unit 500 is in the mirror-down position.

In the state shown in FIG. 8E, the spring 607 urges the shaft portion502 c of the main mirror holder 502 in the mirror-down direction,whereby the first contact portion 502 b of the main mirror holder 502 isbrought into contact with the positioning shaft 507. Further, the spring608 urges the drive shaft portion 504 c of the sub mirror holder 504 inthe mirror-down direction, whereby the first contact portion 504 b ofthe sub mirror holder 504 is brought into contact with the positioningshaft 508.

In this state, an inner peripheral surface of a rectangular hole 604 cof the mirror drive lever 604 is not in contact with the drive shaftportion 504 c of the sub mirror holder 504. With this, only the urgingforce of the spring 608 acts on the sub mirror holder 504, and hence themirror unit 500 is stably positioned in the mirror-down position.

The mirror drive lever unit 700 is urged in the mirror-up direction bythe reaction forces of the springs 607 and 608. As a result, the firstfollower portion 605 c of the mirror drive gear 605 is brought intocontact with the first cam portion 603 d of the cam gear 603. Then, whenthe motor 601 is rotated in the mirror-up direction (counterclockwisedirection as viewed from the pinion 602) in the state shown in FIGS. 8Ato 8E, mirror-up driving of the mirror drive unit 1000 is started, andthe state shown in FIGS. 8A to 8E shifts to a state shown in FIGS. 9A to9E.

FIGS. 9A to 9E are views useful in explaining states of the componentsof the mirror drive unit 100 immediately before the cam gear 603 and themirror drive gear 605 are brought into mesh with each other immediatelyafter the mirror drive unit 1000 starts mirror-up driving.

FIG. 9A is a front view showing a state immediately before the mirrorunit 500 starts the mirror-up operation, which corresponds to FIG. 8A.FIG. 8B is a right side view of FIG. 9A. FIG. 9B shows the relationshipbetween the light shielding plate 603 f of the cam gear 603 and thephoto-interrupters 609 and 610 immediately after the mirror drive unit1000 has started mirror-up driving.

As shown in FIG. 9B, the cam gear 603 is rotated in a counterclockwisedirection as viewed in FIG. 9B from the state shown in FIGS. 8A to 8E.In this state, the state of the photo-interrupter 609 is changed fromthe light-receiving state, shown in FIGS. 8A to 8E, to thenon-light-receiving state, by the light shielding plate 603 f of the camgear 603. Further, the photo-interrupter 610 is shielded from light bythe light shielding plate 603 f of the cam gear 603, thereby continuingto be in the non-light-receiving state. When the state of thephoto-interrupter 609 is changed from the light-receiving state to thenon-light-receiving state, the MPU 100 determines via the mirror drivecircuit 101 that the mirror unit 500 has not completed the mirror-downoperation or the mirror-up operation.

FIG. 9C is a cross-sectional view taken along c-c in FIG. 9A. FIG. 9Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605immediately after the mirror drive unit 1000 has started the mirror-updriving.

In the state shown in FIG. 9C, a first gear tooth 603 g of the cam gear603 enters inside the gear outer circle of the gear portion 605 b of themirror drive gear 605. At this time, as described above, the firstfollower portion 605 c is brought into contact with the first camportion 603 d of the cam gear 603, whereby the mirror drive gear 605 isrestricted from rotating in the mirror-up direction. Therefore, a firstgear tooth 605 e of the mirror drive gear 605 is positioned outside thegear outer circle of the second gear portion 603 c of the cam gear 603.This enables the second gear portion 603 c of the can; gear 603 and thegear portion 605 b of the mirror drive gear 605 to stably shift to ameshed state.

FIG. 9D is a cross-sectional view taken along d-d in FIG. 9A. FIG. 9Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605, immediately after the mirror drive unit 1000 has startedmirror-up driving. In the state shown in FIG. 9D, the first followerportion 605 c of the mirror drive gear 605 is in contact with the firstcam portion 603 d of the cam gear 603. Further, the second cam portion603 e of the cam gear 603 and the second follower portion 605 d of themirror drive gear 605 are not in contact with each other.

FIG. 9E is a cross-sectional view taken along e-e in FIG. 9A. FIG. 9Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608),immediately after the mirror drive unit 1000 has started mirror-updriving.

In the state shown in FIG. 9E, the spring 607 urges the shaft portion502 c of the main mirror holder 502, whereby the first contact portion502 b of the main mirror holder 502 is brought into contact with thepositioning shaft 507. Further, the spring 608 urges the drive shaftportion 504 c of the sub mirror holder 504, whereby the first contactportion 504 b of the sub mirror holder 504 are brought into contact withthe positioning shaft 508. When mirror-up driving by the mirror driveunit 1000 progresses from the state shown in FIGS. 9A to 9E, the stateshown in FIGS. 9A to 9E shifts to a state shown in FIGS. 10A to 10E.

FIGS. 10A to 10E are views useful in explaining states of the componentsof the mirror drive unit 1000 immediately before the mirror unit 500starts a mirror-up operation. FIG. 10A is a front view showing a stateimmediately before the mirror unit 500 starts the mirror-up operation,which corresponds to FIG. 8A. FIG. 10B is a right side view of FIG. 10A.FIG. 10B shows the relationship between the light shielding plate 603 fof the cam gear 603 and the photo-interrupters 600 and 610, immediatelybefore the mirror unit 500 starts the mirror-up operation.

As shown in FIG. 10B, the cam gear 603 is further rotated in thecounterclockwise direction as viewed in FIG. 10B from the state shown inFIGS. 9A to 9E. In this state, the photo-interrupters 609 and 610 areboth shielded from light by the light shielding plate 603 f of the camgear 603, thereby continuing to be in the non-light-receiving state. Atthis time, as described above, the MPU 100 determines via the mirrordrive circuit 101 that the mirror unit 500 has not completed themirror-down operation or the mirror-up operation.

FIG. 10C a cross-sectional view taken along c-c in FIG. 10A. FIG. 10Cshows the relationship between the first cam portion 603 d of the camgear 603 and the first follower portion 605 c of the mirror drive gear605 immediately before the mirror unit 500 starts the mirror-upoperation.

In the state shown in FIG. 10C, the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605 aremeshed with each other. With this, when the cam gear 603 is rotated inthe mirror-up direction (counterclockwise direction as viewed in FIG.10C, the mirror drive lever unit 700 is also rotated in the mirror-updirection (clockwise direction as viewed in FIG. 10C).

Further, at this time, the gear portion 605 b of the mirror drive gear605 starts to be meshed with the second gear portion 603 c, from thefirst gear tooth 603 g of the cam gear 603. The first gear tooth 603 gof the cam gear 603 is larger in width in the circumferential directionthan the other teeth of the second gear portion 603 c. This improves thegear strength of the second gear portion 603 c of the cam gear 603.

FIG. 10D is a cross-sectional view taken along d-d in FIG. 10A. FIG. 10Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605 immediately before the mirror unit 500 starts the mirror-upoperation.

In the state shown in FIG. 10D, the contact state between the first camportion 603 d of the cam gear 603 and the first follower portion 605 cof the mirror drive gear 605 is released. That is, the mirror unit 500is released from the locked state in the mirror-down position.

FIG. 10E is a cross-sectional view taken along e-e in FIG. 10A. FIG. 10Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608),immediately before the mirror unit 500 starts the mirror-up operation.

In the state shown in FIG. 10E, the spring 607 urges the shaft portion502 c of the main mirror holder 502, whereby the first contact portion502 b of the main mirror holder 502 is brought into contact with thepositioning shaft 507.

Here, a region in which when the main mirror holder 502 is in a state inthe mirror-down position, the sub mirror holder 504 is moved in themirror-up direction to a position where the sub mirror holder 504 isoverlaid on the main mirror holder 502 (region from FIGS. 8A to 8E toFIGS. 12A to 12E) is referred to as a first region. Further, a region inwhich the main mirror holder 502 and the sub mirror holder 504 are movedto the mirror-up position in a state overlaid upon each other (regionfrom FIGS. 12A to 12E to FIGS. 14A to 14E) is referred to as a secondregion.

In the state shown in FIG. 10E when in the first region, the spring 608urges the drive shaft portion 504 c of the sub mirror holder 504,whereby the first contact portion 504 b of the sub mirror holder 504 isbrought into contact with the positioning shaft 508. When mirror-updriving of the mirror drive unit 1000 progresses from the state shown inFIGS. 10A to 10E, the state shown in FIGS. 10A to 10E shifts to a stateshown in FIGS. 11A to 11G.

FIGS. 11A to 11E are views useful in explaining states of the componentsof the mirror drive unit 1000 when the sub mirror holder 504 isperforming its mirror-up operation. FIG. 11A is a front view showing astate in which the sub mirror holder 504 is performing its mirror-upoperation, which corresponds to FIG. 8A. FIG. 11B is a right side viewof FIG. 11A. FIG. 11B shows the relationship between the light shieldingplate 603 f of the cam gear 603 and the photo-interrupters 609 and 610when the sub mirror holder 504 is performing its mirror-up operation.

As shown in FIG. 11B, the cam gear 603 is further rotated in thecounterclockwise direction from the state shown in FIGS. 10A to 10E. Inthis state, the photo-interrupters 609 and 610 are both shielded fromlight by the light shielding plate 603 f of the cam gear 603, therebycontinuing to be in the non-light-receiving state. At this time, asmentioned above, the MPU 100 determines via the mirror drive circuit 101that the mirror unit 500 has not completed the mirror-down operation orthe mirror-up operation.

FIG. 11C is a cross-sectional view taken along c-c in FIG. 11A. FIG. 11Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605 whenthe sub mirror holder 504 is performing its mirror-up operation.

In the state shown in FIG. 11C, the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605 aremeshed with each other. Therefore, the driving force of the motor 601 istransmitted to the mirror drive lever unit 700 via the cam gear 603,whereby the mirror drive lever unit 700 is rotated in the mirror-updirection (clockwise direction as viewed in FIG. 11C) from the stateshown in FIGS. 10A to 10E.

FIG. 11D is a cross-sectional view taken along d-d in FIG. 11A. FIG. 11Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605, when the sub mirror holder 504 is performing its mirror-upoperation.

In the state shown in FIG. 11D, the first cam portion 603 d of the camgear 603 and the first follower portion 605 c of the mirror drive gear605 are not in contact with each other. Further, the second cam portion603 e of the cam gear 603 and the second follower portion 605 d of themirror drive gear 605 are not in contact with each other, either.

FIG. 11F is a cross-sectional view taken along e-e in FIG. 11A. FIG. 11Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608), whenthe sub mirror holder 504 is performing its mirror-up operation.

In the state shown in FIG. 11E, the inner peripheral surface of therectangular hole 604 c of the mirror drive lever 604 is brought intocontact with the drive shaft portion 504 c of the sub mirror holder 504,whereby the sub mirror holder 504 is rotated in a direction in which thesub mirror holder 504 is closed to the main mirror holder 502 (mirror-updirection). Further, the spring 608 urges the drive shaft portion 504 cof the sub mirror holder 504. The shaft portion 502 c of the main mirrorholder 502 continues to be in the state urged by the spring 607, andhence the main mirror holder 502 continues to be in the mirror-downstate. When mirror-up driving of the mirror drive unit 1000 progressesfrom the state shown in FIG. 11A to 11E, the state shown in FIG. 11A to11E shifts to a state shown in FIGS. 12A to 12E.

FIGS. 12A to 12E are views useful in explaining states of the componentsof the mirror drive unit 1000 when the main mirror holder 502 starts itsmirror-up operation. FIG. 12A is a front view showing a state at themoment when the main mirror holder 502 starts its mirror-up operation,which corresponds to FIG. 8A. FIG. 12B is a right side view of FIG. 12A.FIG. 12B shows the relationship between the light shielding plate 603 fof the cam gear 603 and the photo-interrupters 609 and 610 when the mainmirror holder 502 starts its mirror-up operation.

As shown in FIG. 12B, the cam gear 603 is further rotated in thecounterclockwise direction from the state shown in FIGS. 11A to 11E. Inthis state, the photo-interrupters 609 and 610 are both shielded fromlight by the light shielding plate 603 f of the cam gear 603, continuingto be in the non-light-receiving state. At this time, as mentionedabove, the MPU 100 determines via the mirror drive circuit that themirror unit 500 has not completed the mirror-down operation or themirror-up operation.

FIG. 12C is a cross-sectional view taken along c-c in FIG. 12A. FIG. 12Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605 at themoment when the main mirror holder 502 starts its mirror-up operation.

In the state shown in FIG. 12C, the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605 are inmesh with each other. Therefore, the driving force of the motor 601 istransmitted to the mirror drive lever unit 700 via the cam gear 603,whereby the mirror drive lever unit 700 is further rotated in themirror-up direction (clockwise direction as viewed in FIG. 12C) from thestate shown in FIGS. 11A to 11E.

FIG. 12D is a cross-sectional view taken along d-d in FIG. 12A. FIG. 12Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605 at the moment when the main mirror holder 502 starts itsmirror-up operation.

In the state shown in FIG. 12D, the first cam portion 603 d of the camgear 603 and the first follower portion 605 c of the mirror drive gear605 are not in contact with each other. Further, the second cam portion603 e of the cam gear 603 and the second follower portion 605 d of themirror drive gear 605 are not in contact with each other, either.

FIG. 12E is a cross-sectional view taken along e-e in FIG. 12A. FIG. 12Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608), atthe moment when the main mirror holder 502 starts its mirror-upoperation.

In the state shown in FIG. 12E, the inner peripheral surface of therectangular hole 604 c of the mirror drive lever 604 is in contact withthe drive shaft portion 504 c of the sub mirror holder 504, whereby thesub mirror holder 504 is rotated in the direction in which the submirror holder 504 is closed to the main mirror holder 502 (mirror-updirection), to be placed in a state overlaid on the main mirror holder502.

The spring 607 is pressed and urged by a spring urging portion 604 e ofthe mirror drive lever 604. In this state, the shaft portion 502 c ofthe main mirror holder 502 is not in contact with the spring 607, and isnot urged by the spring 607. This makes it possible to reduce the loadapplied when the main mirror holder 502 is rotated in the mirror-updirection.

Further, a second contact portion 502 e of the main mirror holder 502 isin contact with a second contact portion 504 d of the sub mirror holder504. The main mirror holder 502 is rotated in the mirror-up direction bybeing pushed up by the sub mirror holder 504. At this time, the downlever portion 604 g of the mirror drive lever 604 passes outside therotation locus of the shaft portion 502 c of the main mirror holder 502.When mirror-up driving of the mirror drive unit 1000 progresses from thestate shown in FIGS. 12A to 12E, the state shown in FIGS. 12A to 12Eshifts to a state shown in FIGS. 13A to 13E.

FIGS. 13A to 13E are views useful in explaining states of the componentsof the mirror drive unit 1000 immediately before the mirror unit 500completes the mirror-up operation. FIG. 13A is a front view showing astate immediately before the mirror unit 500 completes the mirror-upoperation, which corresponds to FIG. 8A. FIG. 13B is a right side viewof FIG. 13A. FIG. 13B shows the relationship between the light shieldingplate 603 f of the cam gear 603 and the photo-interrupters 609 and 610immediately before the mirror unit 500 completes the mirror-upoperation.

As shown in FIG. 13B, the cam gear 603 is further rotated in thecounterclockwise direction from the state shown in FIGS. 12A to 12E. Inthis state, the photo-interrupters 609 and 610 are both shielded fromlight by the light shielding plate 603 f of the cam gear 603, continuingto be in the non-light-receiving state. At this time, as mentionedabove, the MPU 100 determines via the mirror drive circuit 101 that themirror unit 500 has not completed the mirror-down operation or themirror-up operation.

FIG. 13C is a cross-sectional view taken along c-c in FIG. 13A. FIG. 13Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605immediately before the mirror unit 500 completes the mirror-upoperation. In the state shown in FIG. 13C, the second gear portion 603 cof the cam gear 603 and the gear portion 605 b of the mirror drive gear605 are released from the meshed state, to enter a non-meshed state.

FIG. 13D is a cross-sectional view taken along d-d in FIG. 13A. FIG. 13Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605, immediately before the mirror unit 500 completes the mirror-upoperation

In the state shown in FIG. 13D, the second cam portion 603 e of the camgear 603 is in contact with the second follower portion 605 d of themirror drive gear 605, and the cam gear 603 is rotated in thecounterclockwise direction to thereby push up the mirror drive gear 605in the mirror-up direction. This causes the mirror drive lever unit 700to rotate in the mirror-up direction. Further, the first cam portion 603d of the cam gear 603 is not in contact with the first follower portion605 c of the mirror drive gear 605.

FIG. 13E is a cross-sectional view taken along e-e in FIG. 13A. FIG. 13Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608),immediately before the mirror unit 500 completes the mirror-upoperation.

In the state shown in FIG. 13E, the drive shaft portion 504 c of the submirror holder 504 is in contact with the inner peripheral surface of therectangular hole 604 c of the mirror drive lever 604, and the sub mirrorholder 504 performs the mirror-up operation. Further, the second contactportion 502 e of the main mirror holder 502 in contact with the secondcontact portion 504 d of the sub mirror holder 504, whereby the mainmirror holder 502 performs the mirror-up operation by being pushed up bythe sub mirror holder 504.

At this time, the down lever portion 604 g of the mirror drive lever 604enters the rotation locus of the shaft, portion 502 c of the main mirrorholder 502. In a case where the main mirror holder 502 is moved awayfrom the sub mirror holder 504, the shaft portion 502 c of the mainmirror holder 502 is brought into contact with the down lever portion604 g of the mirror drive lever 604. When mirror-up driving of themirror drive unit 1000 progresses from the state shown in FIGS. 13A to13E, the state shown in FIGS. 13A to 13E shifts to a state shown inFIGS. 14A to 14E.

FIGS. 14A to 14E are views useful in explaining states of the componentsof the mirror drive unit 1000 when the mirror unit is in the mirror-upposition. FIG. 14A is a front view showing a state when the mirror unit500 is in the mirror-up position, which corresponds to FIG. 8A. FIG. 14Bis a right side view of FIG. 14A. FIG. 14B shows the relationshipbetween the light shielding plate 603 f of the cam gear 603 and thephoto-interrupters 609 and 610 when the mirror unit 500 is in themirror-up position.

In the state shown in FIG. 14B, the cam gear 603 is further rotated inthe counterclockwise direction from the state shown in FIGS. 13A to 13E.In this state, the photo-interrupter 609 is shielded from light by thelight shielding plate 603 f of the cam gear 603, continuing to be in thenon-light-receiving state, and the photo-interrupter 610 is releasedfrom the state shielded from light by the light shielding plate 603 f ofthe cam gear 603 to enter the light-receiving state.

At this time, the MPU 100 determines via the mirror drive circuit 101that the mirror unit 500 has completed the mirror-up operation, andterminates mirror-up driving of the mirror drive unit 1000.

FIG. 14C is a cross-sectional view taken along c-c in FIG. 14A. FIG. 14Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605 whenthe mirror unit 500 is in the mirror-up position. In the state shown inFIG. 14C, the second gear portion 603 c of the cam gear 603 is not inmesh with the gear portion 605 b of the mirror drive gear 605.

FIG. 14D is a cross-sectional view taken along d-d in FIG. 14A. FIG. 14Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605, when the mirror unit 500 is in the mirror-up position.

In the state shown in FIG. 14D, the second follower portion 605 d of themirror drive gear 605 is in contact, in the urged state, with the secondcam portion 603 e of the cam gear 603. The second cam portion 603 e ofthe cam gear 603 has a circular arc cam shape concentric with the partof the cam gear 603 without a cam lift, as mentioned above. Therefore,even when the cam gear 603 is rotated to some degree in the cam area ofthe first cam portion 603 d in this state, rotation is not transmittedto the mirror drive gear 605, so that the mirror drive gear 605 is notrotated.

Further, in this state, when the mirror drive gear 605 is brought intocontact with the cam gear 603 in a state urged in the mirror-downdirection, the mirror drive gear 605 is brought, into contact with thecam gear 603 such that the urging force acts in a directionsubstantially toward the center of rotation of the cam gear 603.Therefore, in this state, unless the cam gear 603 is rotated, the mirrordrive gear 605 is restricted from rotating in the mirror-down direction.This causes the mirror unit 500 to be locked in the mirror-up position.

FIG. 14E is a cross-sectional view taken along e-e in FIG. 14A. FIG. 14Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608), whenthe mirror unit 500 is in the mirror-up position.

In the state shown in FIG. 14E, the drive shaft portion 504 c of the submirror holder 504 is in contact with the inner peripheral surface of therectangular hole 604 c of the mirror drive lever 604, and the secondcontact portion 502 e of the main mirror holder 502 is in contact withthe second contact portion 504 d of the sub mirror holder 504.

The main mirror holder 502 is in contact with the stopper 505 in a statein which the front end portion thereof elastically deforms the stopper505. This causes the main mirror holder 502 to receive the urging forcein the mirror-down direction, and the second follower portion 605 d ofthe mirror drive gear 605 is in contact with the second cam portion 603e of the cam gear 603.

Further, in this state, the mirror drive lever 604 receives the urgingforce in the mirror-up direction, and the mirror unit 500 is also pushedin the mirror-up direction. At this time, the down lever portion 604 gof the mirror drive lever 604 is not in contact with the shaft portion502 c of the main mirror holder 502, and is on standby within therotation locus of the shaft portion 502 c of the main mirror holder 502.When the motor 601 rotates in the mirror-down direction (clockwisedirection as viewed from the pinion 602) in the state shown in FIGS. 14Ato 14E, and the mirror drive unit 1000 starts mirror-down driving, thestate shown in FIGS. 14A to 14E shifts to a state shown in FIGS. 15A to15E.

FIGS. 15A to 15E are views useful in explaining states of the componentsof the mirror drive unit 1000 immediately after the mirror drive unit1000 starts mirror-down driving. FIGS. 15A to 15E show a stateimmediately after driving of the motor 601 has been started to move themain mirror holder 502 and the sub mirror holder 504 from the mirror-upposition toward the mirror-down position.

FIG. 15A is a front view showing a state immediately after the mirrordrive unit 1000 has started mirror-down driving, which corresponds toFIG. 8A. FIG. 15B is a right side view of FIG. 15A. FIG. 15B shows therelationship between the light shielding plate 603 f of the cam gear 603and the photo-interrupters 609 and 610 immediately after the mirrordrive unit 1000 has started mirror-down driving.

In the state shown in FIG. 15B, the cam gear 603 is rotated in themirror-down direction (clockwise direction as viewed in FIG. 15B), andthe photo-interrupter 610 is shielded from light by the light shieldingplate 603 f of the cam gear 603, so that the state of thephoto-interrupter 610 is changed from the light-receiving state to thenon-light-receiving state. The photo-interrupter 609 is shielded fromlight by the light shielding plate 603 f of the cam gear 603, continuingto be in the non-light-receiving state.

When the state of the photo-interrupter 610 is changed from thelight-receiving state to the non-light-receiving state, the MPU 100determines via the mirror drive circuit 101 that the mirror unit 500 hasnot completed the mirror-down operation or the mirror-up operation.

FIG. 15C is a cross-sectional view taken along c-c in FIG. 15A. FIG. 15Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605immediately after the mirror drive unit 1000 has started mirror-downdriving.

In the state shown in FIG. 15C, a second gear tooth 603 h of the camgear 603 enters inside the gear outer circle of the gear portion 605 bof the mirror drive gear 605. At this time, as described hereinafterwith reference to FIG. 15D, the second follower portion 605 d of themirror drive gear 605 is in contact with the second cam portion 603 e ofthe cam gear 603, whereby the mirror drive gear 605 is restricted fromrotating in the mirror-down direction. Therefore, a second gear tooth605 f of the mirror drive gear 605 is positioned outside the gear outercircle of the second gear portion 603 c of the cam gear 603. Thisenables the second gear portion 603 c of the cam gear 603 and the gearportion 605 b of the mirror drive gear 605 to stably shift to a meshedstate.

FIG. 15D is a cross-sectional view taken along d-d in FIG. 15A. FIG. 15Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605, immediately after the mirror drive unit 1000 has startedmirror-down driving. In the state shown in FIG. 15D, the second camportion 603 e of the cam gear 603 is in contact with the second followerportion 605 d of the mirror drive gear 605.

FIG. 15E is a cross-sectional view taken along e-e in FIG. 15A. FIG. 15Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608),immediately after the mirror drive unit 1000 has started mirror-down

In the state shown in FIG. 15E, the drive shaft portion 504 c of the submirror holder 504 is in contact with inner peripheral surface of therectangular hole 604 c of the mirror drive lever 604, and the secondcontact portion 502 e of the main mirror holder 502 is in contact withthe second contact portion 504 d of the sub mirror holder 504.

FIGS. 16A to 16E are views useful in explaining states of the componentsof the mirror drive unit 1000 immediately before the mirror unit 500starts the mirror-down operation. FIGS. 16A to 16E show a stateimmediately after driving of the mirror drive lever 604 has been startedto move the main mirror holder 502 and the sub mirror holder 504 fromthe mirror-up position toward the mirror-down position.

FIG. 16A is a front view showing a state immediately before the mirrorunit 500 starts the mirror-down operation, which corresponds to FIG. 8A.FIG. 16B is a right side view of FIG. 16A. FIG. 16B shows therelationship between the light shielding plate 603 f of the cam gear 603and the photo-interrupters 609 and 610 immediately before the mirrorunit 500 starts the mirror-down operation.

As shown in FIG. 16B, the cam gear 603 is further rotated in theclockwise direction from the state shown in FIGS. 15A to 15E. In thisstate, the photo-interrupters 609 and 610 are both shielded from lightby the light shielding plate 603 f of the cam gear 603, and are in thenon-light-receiving state. At this time, as mentioned above, the MPU 100determines via the mirror drive circuit 101 that the mirror unit 500 hasnot completed the mirror-down operation or the mirror-up operation.

FIG. 16C is a cross-sectional view taken along c-c in FIG. 16A. FIG. 16Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605immediately before the mirror unit 500 starts the mirror-down operation.

In the state shown in FIG. 16C, the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605 areshifted to the meshed state. With this, when the cam gear 603 is rotatedin the mirror-down direction (clockwise direction as viewed in FIG.16C), the mirror drive lever unit 700 is also rotated in the mirror-downdirection (counterclockwise direction as viewed in FIG. 16C).

At this time, the second gear portion 603 c of the cam gear 603 startsto be meshed with the gear portion 605 b of the mirror drive gear 605from the second gear tooth 605 f of the mirror drive gear 605. Thesecond gear tooth 603 h of the cam gear 603 is larger in width in thecircumferential direction than the other teeth of the second gearportion 603 c. This improves the gear strength of the second gearportion 603 c of the cam gear 603.

FIG. 16D is a cross-sectional view taken along d-d in FIG. 16A. FIG. 16Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605, immediately before the mirror unit 500 starts the mirror-downoperation. In the state shown in FIG. 16D, the contact state between thesecond cam portion 603 e of the cam gear 603 and the second followerportion 605 d of the mirror drive gear 605 is released.

FIG. 16F is a cross-sectional view taken along e-e in FIG. 16A. FIG. 16Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608),immediately before the mirror unit 500 starts the mirror-down operation.

In the state shown in FIG. 16E, the inner peripheral surface of therectangular hole 604 c of the mirror drive lever 604 is in contact withthe drive shaft portion 504 c of the sub mirror holder 504, and the downlever portion 604 g of the mirror drive lever 604 in contact with theshaft portion 502 c of the main mirror holder 502. With this, when themirror drive lever 604 is rotated in the mirror-down direction, the submirror holder 504 and the main mirror holder 502 can quickly rotate inthe mirror-down direction. Therefore, it is possible to reduce the timerequired for the main mirror 501 to reach the mirror-down position,which makes it possible to reduce time over which an object image islost during finder observation. When mirror-down driving of the mirrordrive unit 1000 progresses from the state shown in FIGS. 16A to 16E, thestate shown in FIGS. 16A to 16E shifts to a state shown in FIGS. 17A to17E.

FIGS. 17A to 17E are views useful in explaining states of the componentsof the mirror drive unit 1000 when the main mirror holder 502 reachesits mirror-down position. FIG. 17A is a front view showing a state atthe moment when the main mirror holder 502 reaches its mirror-downposition, which corresponds to FIG. 8A. FIG. 17B is a right side view ofFIG. 17A. FIG. 17B shows the relationship between the light shieldingplate 603 f of the cam gear 603 and the photo-interrupters 609 and 610at the moment when the main mirror holder 502 reaches its mirror-downposition.

In the state shown in FIG. 17B, the cam gear 603 further rotated in theclockwise direction from the state shown in FIGS. 16A to 16E. In thisstate, the photo-interrupters 609 and 610 are both shielded from lightby the light shielding plate 603 f of the cam gear 603, and are in thenon-light-receiving state. At this time, as mentioned above, the MPU 100determines via the mirror drive circuit 101 that the mirror unit 500 hasnot completed the mirror-down operation or the mirror-up operation.

FIG. 17C is a cross-sectional view taken along c-c in FIG. 17A. FIG. 17Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605 at themoment when the main mirror holder 502 reaches its mirror-down position.

In the state shown in FIG. 17C, the second gear portion 603 c of the camgear 603 is in mesh with the gear portion 605 b of the mirror drive gear605. Therefore, the driving force of the motor 601 is transmitted to themirror drive lever unit 700 via the cam gear 603, whereby the mirrordrive lever unit 700 is rotated in the mirror-down direction(counterclockwise direction as viewed in FIG. 17C) from the state shownin FIGS. 16A to 16E.

FIG. 17D is a cross-sectional view taken along d-d in FIG. 17A. FIG. 17Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605 at the moment when the main mirror holder 502 reaches itsmirror-down position.

In the state shown in FIG. 17D, the second cam portion 603 e of the camgear 603 and the second follower portion 605 d of the mirror crave gear605 are not in contact with each other. Further, the first cam portion603 d of the cam gear 603 and the first follower portion 605 c of themirror drive gear 605 are not in contact with each other, either.

FIG. 17E is a cross-sectional view taken along e-e in FIG. 17A. FIG. 17Fshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608), atthe moment when the main mirror holder 502 reaches its mirror-downposition.

In the state shown in FIG. 17E, the inner peripheral surface of therectangular hole 604 c of the mirror drive lever 604 is in contact withthe drive shaft portion 501 c of the sub mirror holder 504, whereby thesub mirror holder 504 is rotated in the mirror-down direction. At thistime, the down lever portion 604 g of the mirror drive lever 604 passesoutside the rotation locus of the shaft portion 502 c of the main mirrorholder 502. In this state, the main mirror holder 502 is pulled down bythe sub mirror holder 504 to thereby perform the mirror-down operation.

Further, the first contact portion 502 b of the main mirror holder 502is brought into contact with the positioning shaft 507, and when themain mirror holder 502 bounces after the contact, the main mirror holder502 is rotated about the rotational shaft 502 a in the mirror-updirection (clockwise direction as viewed in FIG. 17E). At this time, theshaft portion 502 c of the main mirror holder 502 is brought intocontact with the spring 607, to receive the urging force in themirror-down direction. This is suppresses the bounce of the main mirrorholder 502.

As mentioned above, the inner peripheral surface of the rectangular hole604 c of the mirror drive lever 604 is in contact with the drive shaftportion 504 c of the sub mirror holder 504, whereby the sub mirrorholder 504 continues the mirror-down operation. When mirror-down drivingof the mirror drive unit 1000 progresses from the state shown in FIGS.17A to 17E, the state shown in FIGS. 17A to 17E shifts to a state shownin FIGS. 18A to 18E.

FIGS. 18A to 18E are views useful in explaining states of the componentsof the mirror drive unit 1000 immediately before the sub mirror holder504 reaches its mirror-down position. FIG. 18A is a front view showing astate immediately before the sub mirror holder 504 reaches itsmirror-down position, which corresponds to FIG. 8A. FIG. 18E is a rightside view of FIG. 18A. FIG. 18B shows the relationship between the lightshielding plate 603 f of the cam gear 603 and the photo-interrupters 609and 610 immediately before the sub mirror holder 504 reaches itsmirror-down position.

In the state shown in FIG. 18B, the cam gear 603 is further rotated inthe clockwise direction as viewed in FIG. 18B from the state shown inFIGS. 17A to 17E. In this state, the photo-interrupters 609 and 610 areboth shielded from light by the light shielding plate 603 f of the camgear 603, and are in the non-light-receiving state. At this time, asmentioned above, the MPU 100 determines via the mirror drive circuit 101that the mirror unit 500 has not completed the mirror-down operation orthe mirror-up operation.

FIG. 18C is a cross-sectional view taken along c-c in FIG. 18A. FIG. 18Cshows the relationship between the second gear portion 603 c of the camgear 603 and the gear portion 605 b of the mirror drive gear 605immediately before the sub mirror holder 504 reaches its mirror-downposition. In the state shown in FIG. 18C, the second gear portion 603 cof the cam gear 603 and the gear portion 605 b of the mirror drive gear605 are released from the meshed state, to enter a non-meshed state.

FIG. 18D is a cross-sectional view taken along d-d in FIG. 18A. FIG. 18Dshows the relationship between the first cam portion 603 d and thesecond cam portion 603 e of the cam gear 603, and the first followerportion 605 c and the second follower portion 605 d of the mirror drivegear 605, immediately before the sub mirror holder 504 reaches itsmirror-down position.

In the state shown in FIG. 18D, the first cam portion 603 d of the camgear 603 is brought into contact with the first follower portion 605 cof the mirror drive gear 605, and pushes down the mirror drive gear 605in the mirror-down direction (counterclockwise direction as viewed inFIG. 18D). This causes the mirror drive lever unit 700 to be rotated inthe mirror-down direction. Further, the second cam portion 603 e of thecam gear 603 is not in contact with the second follower portion 605 d ofthe mirror drive gear 605.

FIG. 18E is a cross-sectional view taken along e-e in FIG. 18A. FIG. 18Eshows the relationship between the main mirror holder 502 and the submirror holder 504, and the mirror drive lever unit 700 (the mirror drivelever 604, the mirror drive gear 605, and the springs 607 and 608),immediately before the sub mirror holder 504 reaches its mirror-downposition.

In the state shown in FIG. 18E, the spring 607 urges the shaft portion502 c of the main mirror holder 502, whereby the first contact portion502 b of the main mirror holder 502 is in contact with the positioningshaft 507. Further, the inner peripheral surface of the rectangular hole604 c of the mirror drive lever 604 is in contact with the drive shaftportion 504 c of the sub mirror holder 504, whereby the sub mirrorholder 504 continues the mirror-down operation. When mirror-down drivingof the mirror drive unit 1000 progresses from the state shown in FIGS.18A to 18E, the state shown in FIGS. 18A to 18E shifts to themirror-down state shown in FIGS. 8A to 8E.

In FIGS. 8A to 8E, as described above, the mirror unit 500 is in themirror-down position. In this state, as shown in FIG. 8B, thephoto-interrupter 609 is released from the state shielded from light bythe light shielding plate 603 f of the cam gear 603, to enter thelight-receiving state, and the photo-interrupter 610 is shielded fromlight by the light shielding plate 603 f of the cam gear 603, continuingto be in the non-light-receiving state. At this time, the MPU 100determines via the mirror drive circuit that the mirror unit 500 hascompleted the mirror-up operation or the mirror-down operation, andterminates the mirror driving. In the state shown in FIG. 8C, the secondgear portion 603 c of the cam gear 603 and the gear portion 605 b of themirror drive gear 605 are not in mesh with each other.

Further, in the state shown in FIG. 8D, the first cam portion 603 d ofthe cam gear 603 is in contact with the first follower portion 605 c ofthe mirror drive gear 605. The first cam portion 603 d of the cam gear603 has a circular arc cam shape concentric with the part of the camgear 603 without a cam lift. Therefore, even when the cam gear 603 isrotated to some degree in the cam area of the first cam portion 603 d inthis state, rotation is not transmitted to the mirror drive gear 605, sothat the mirror drive gear 605 is not rotated.

Further, in this state, when the mirror drive gear 605 in contact withthe cam gear 603receives a urging force in the mirror-up direction, theurging force acts in the direction substantially toward the center ofrotation of the cam gear 603. Therefore, in the state shown in FIG. 8D,unless the cam gear 603 is rotated, the mirror drive gear 605 isrestricted from rotating in the mirror-up direction. This causes themirror unit 500 to be locked in the mirror-down. position.

Further, the first contact portion 504 b of the sub mirror holder 504 isbrought into contact with the positioning shaft 508, and when the submirror holder 504 bounces, the sub mirror holder 504 is rotated aboutthe support hole 504 a in the mirror-up direction (counterclockwisedirection as viewed in FIG. 8D). At this time, the drive shaft portion504 c of the sub mirror holder 504 charges the spring 608, and thebounce of the sub mirror holder 504 is suppressed. This makes itpossible to reduce the driving sound of the mirror unit 500.

As described above, in the present embodiment, the driving force fromthe motor 601 is transmitted to the sub mirror holder 504 to therebyrotate the mirror unit 500 between the mirror-down position and themirror-up position. This eliminates the need of a toggle spring or areversing cam for driving the sub mirror holder 504. Further, theamounts of charging of the spring 607 and the spring 608 for urging themain mirror holder 502 and the sub mirror holder 504, respectively, canbe reduced. This makes it possible to provide a mirror drive device thatis capable of achieving lower torque and higher speed in driving of themirror unit 500, and also improving durability thereof.

FIG. 19A is a graph showing the relationship between the position of themirror unit 500 and time in the mirror-up operation, and FIG. 19B is agraph showing the relationship between the position of the mirror unit500 and time in the mirror-down operation. The mirror-up operation inFIG. 19A corresponds to the operation described with reference to FIGS.8A to 8E to FIGS. 14A to 14E, and the mirror-down operation in FIG. 19Bcorresponds to the operation described with reference to FIGS. 15A to15E to FIGS. 18A to 18E and FIGS. 8A to 8E.

Next, a description will be given of control of driving of the mirrorunit 500 with reference to FIGS. 20A and 20B. FIG. 20A is a flowchart ofa mirror drive control process performed during the mirror-up operationof the mirror unit 500, and FIG. 20B is a flowchart of a mirror drivecontrol process performed during the mirror-down operation of the mirrorunit 500. The processes in FIGS. 20A and 20B are performed e.g. by theMPU 100 that loads the programs stored in a storage section, such as theEEPROM 100 a, into a RAM, not shown.

First, the mirror drive control process in the mirror-up operation ofthe mirror unit 500 will be described with reference to FIG. 20A. In astep S200, when the release button is fully pressed in the mirror-downstate shown in FIGS. 8A to 8E, causing the release switch (SW2) 7 b tobe turned on, the MPU 100 controls the mirror drive circuit 101 to causethe motor 601 to rotate in the mirror-up direction, and proceeds to astep S201. With this, the sub mirror holder 504 starts to rotate in themirror-up direction.

In the step S201, when the rotation of the motor 601 causes the state ofthe photo-interrupter 609 to be changed from the light-receiving stateto the non-light-receiving state, the MPU 100 proceeds to a step S202.In the step S202, the MPU 100 controls the mirror drive circuit 101 tostart counting of pulses from the motor 601, and proceeds to a stepS203.

In the step S203, as shown in FIG. 20A, when the count value of thepulses from the motor 601, which is counted by the mirror drive circuit101, reaches a predetermined value A, the MPU 100 proceeds to a stepS204. Here, the time at which the count value reaches A is a time atwhich the sub mirror holder 504 is rotated to a phase in which the submirror holder 504 is in a position closer to its mirror-down positionthan when the sub mirror holder 504 is in the position in contact withthe main mirror holder 502, shown in FIGS. 12A to 12E.

Here, the rotational position of the sub mirror holder 504 at which thepulse count value reaches A corresponds to a predetermined first settingposition in the mirror-up operation. In the present embodiment, therotational position of the sub mirror holder 504 at which the pulsecount value reaches A is set to a position closer to the position wherethe sub mirror holder 504 is brought into contact with the main mirrorholder 502 than to a substantially midpoint position of a range throughwhich the sub mirror holder 504 is moved from the mirror-down positionto the position where the sub mirror holder 504 is brought into contactwith the main mirror holder 502 (see FIG. 19A).

In the step S204, the MPU 100 controls the mirror drive circuit 101 toreduce the speed of the motor 601 to thereby reduce the rotational speedof the sub mirror holder 504, and proceeds to a step S205. With this, asshown in FIGS. 12A to 12E, and 19A, the sub mirror holder 504 which isreduced in speed is brought into contact with the main mirror holder502.

In the step S205, when the count value of the pulses from the motor 601,which is counted by the mirror drive circuit 101, reaches apredetermined value B, the MPU 100 proceeds to a step S206. Here, thetime at which the pulse count value reaches B is substantially the sametime at which the sub mirror holder 504 is brought into contact with themain mirror holder 502.

In the step S206, when it is detected in the step S205 that the submirror holder 504 is brought into contact with the main mirror holder502, the MPG 100 controls the mirror drive circuit 101 to accelerate themotor 601 in the mirror-up direction, and proceeds to a step S207. Withthis, the main mirror holder 502 starts its mirror-up operation at highspeed in a state in which the sub mirror holder 504 is overlaid thereonin contact therewith, as shown in FIG. 19A.

In the step S207, when the count value of the pulses from the motor 601,which is counted by the mirror drive circuit 101, reaches apredetermined value C, the MPU 100 proceeds to a step S208. Here, thetime at which the pulse count value reaches C is a time at which themirror unit 500 is rotated to a phase in which the mirror unit 500 is ina position closer to the mirror-down position than when the mirror unit500 is in a position reaching the mirror-up position (shown in FIGS. 14Ato 14E).

Here, the rotational position of the mirror unit 500 at which the pulsecount value reaches C corresponds to a predetermined second settingposition in the mirror-up operation. In the present embodiment, therotational position of the mirror unit 500 at which the pulse countvalue reaches C is set to a position closer to the mirror-up positionthan a midpoint position of a range through which the main mirror holder502 is moved from the mirror-down position to the mirror-up position(see FIG. 19A).

In the step S208, the MPU 100 controls the mirror drive circuit 101 toreduce the speed of the motor 601, and proceeds to a step S209. Withthis, as shown in FIG. 19A, the sub mirror holder 504 and the mainmirror holder 502 are reduced in speed again before the mirror unit 500reaches the mirror-up position (shown in FIGS. 14A to 14E).

In the step S209, when the state of the photo-interrupter 610 is changedfrom the non-light-receiving state to the light-receiving state, the MPU100 proceeds to a step S210. In the step S210, the MPU 100 determinesthat the mirror unit 500 has reached the mirror-up position shown inFIG. 14A to 14E, and controls the mirror drive circuit 101 to stopdriving of the motor 601, followed by terminating mirror-up driving.

Next, the mirror drive control process in the mirror-down operation ofthe mirror unit 500 will be described with reference to FIG. 20B. In astep S220, the MPU 100 controls the mirror drive circuit 101 to causethe motor 601 to rotate in the mirror-down direction at the mirror-upposition of the mirror unit 500, shown in FIGS. 15A to 15E, and proceedsto a step S221. With this, the mirror unit 500 starts the mirror-downoperation.

In the step S221, when the mirror drive circuit 101 causes the motor 601to rotate in the mirror-down direction, causing the state of thephoto-interrupter 610 to be changed from the light-receiving state tothe non-light-receiving state, the MPU 100 proceeds to a step S222. Inthe step S222, the MPU 100 controls the mirror drive circuit 101 tostart counting of pulses from the motor 601, and proceeds to a stepS223.

In the step S223, when the count value of the pulses from the motor 601,which is counted by the mirror drive circuit 101, reaches apredetermined value D, the MPU 100 proceeds to a step S224. Here, thetime at which the pulse count value reaches D is a time at which themain mirror holder 502 is rotated to a phase in which the main mirrorholder 502 is in a position closer to the mirror-up position than whenthe main mirror holder 502 is in the position reaching the mirror-downposition, shown in FIGS. 17A to 17E.

Here, the rotational position of the mirror unit 500 at which the pulsecount value reaches D corresponds to a predetermined first settingposition in the mirror-down operation. In the present embodiment, therotational position of the mirror unit 500 at which the pulse countvalue reaches D is set to a position closer to the mirror-down positionthan to a midpoint position of a range through which the main mirrorholder 502 is moved from the mirror-up position to the mirror-downposition (see FIG. 19B).

In the step S224, the MPU 100 controls the mirror drive circuit 101 toreduce the speed of the motor 601 to thereby reduce the rotational speedof the mirror unit 500, and proceeds to a step S225. With this, as shownin FIGS. 17A to 17E, and B, the main mirror holder 502 reaches themirror-down position at a reduced speed.

In the step S225, when the count value of the pulses from the motor 601,which is counted by the mirror drive circuit 101, reaches apredetermined value E, the MPU 100 proceeds to a step S226. Here, thetime at which the count value reaches F is substantially the same timeat which the main mirror holder 502 reaches the mirror-down position,shown in FIGS. 17A to 17E.

In the step S226, when it is detected that the main mirror holder 502has reached the mirror-down position, shown in FIGS. 17A to 17E, the MPU100 controls the mirror drive circuit 101 to accelerate the motor 601 inthe mirror-down direction, and proceeds to a step S227. With this, thesub mirror holder 504 is accelerated and rotated in the mirror-downdirection again when the main mirror holder 502 has reached themirror-down position.

In the step S227, when the count value of the pulses from the motor 601,which is counted by the mirror drive circuit 101, reaches apredetermined value F, the MPU 100 proceeds to a step S228. Here, thetime at which the pulse count value reaches F is a time at which the submirror holder 504 is rotated to a phase in which the sub mirror holder504 is in a position closer to its mirror-up position than when the submirror holder 504 is in a position reaching the mirror-down position,shown in FIGS. 8A to 8E.

Here, the rotational position of the sub mirror holder 504 at which thepulse count value reaches F corresponds to a predetermined secondsetting position in the mirror-down operation. In the presentembodiment, the rotational position of the mirror unit 500 at which thepulse count value reaches F is set to a position closer to themirror-down position of the sub mirror holder 504 than to asubstantially midpoint position of a range through which the sub mirrorholder 504 is moved from the position where the main mirror holder 502reaches its mirror-down position to the mirror-down position of the submirror holder 504.

In the step S228, the MPU 100 controls the mirror drive circuit 101 toreduce the speed of the motor 601, and proceeds to a step S229. Withthis, the sub mirror holder 504 is rotated in the mirror-down directionat a reduced speed, and reaches the mirror-down position.

In the step S229, when the state of the photo-interrupter 609 is changedfrom the non-light-receiving state to the light-receiving state, the MPU100 proceeds to a step S230. In the step S230, the MPU 100 determinesthat the mirror unit 500 has reached the mirror-down position, andcontrols the mirror drive circuit 101 to stop driving of the motor 601,followed by terminating mirror-down driving.

As described above, in the present embodiment, in the mirror-upoperation, it is possible to reduce the impact caused when the submirror holder 504 and the main mirror holder 502 are brought intocontact with each other, and the impact caused when the mirror unit 500reaches the mirror-up position. Therefore, it is possible to suppressthe mirror bounce, and reduce the mirror driving sound in the mirror-upoperation of the mirror unit 500.

Further, in the present embodiment, in the mirror-down operation, it ispossible to reduce the impact caused when the main mirror holder 502 andthe sub mirror holder 504 are brought into contact with the positioningshaft 507 and the positioning shaft 508 at the respective mirror-downpositions. This makes it possible to suppress the mirror bounce, andreduce the mirror driving sound in the mirror-down operation of themirror unit 500.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Applications No.2015-242910 filed Dec. 14, 2015 and No. 2015-242911, filed Dec. 14,2015, which are hereby incorporated by reference herein in theirentirety.

What is claimed is:
 1. A mirror drive device comprising: a first mirrorholder that holds a first mirror and is configured to be movable betweena first position in a photographing optical path and a second positionretracted from the photographing optical path; a second mirror holderthat holds a second mirror in a state rotatably attached to said firstmirror holder and is configured to be movable between a third positionin the photographing optical path and a fourth position retracted fromthe photographing optical path; a motor; and a driving member configuredto be driven by said motor to thereby move said second mirror holderbetween the third position and the fourth position, wherein said drivingmember moves said second mirror holder from the third position to thefourth position, whereby said first mirror holder is moved from thefirst position to the second position.
 2. The mirror drive deviceaccording to claim 1, wherein when said second mirror holder is movedfrom the third position to the fourth position by said driving member,the mirror drive device has a first region in which said second mirrorholder is moved without the first mirror holder being moved, and asecond region in which said first mirror holder and said second mirrorholder are both moved.
 3. The mirror drive device according to claim 2,further comprising an urging member configured to urge said first mirrorholder toward the first position, and wherein in the second region, saidurging member does not urge said first mirror holder toward the firstposition.
 4. The mirror drive device according to claim 2, wherein inthe second region, said first mirror holder and said second mirrorholder are moved in a state overlaid upon each other.
 5. The mirrordrive device according to claim 1, wherein said driving member includesa contact portion that is brought into contact with said first mirrorholder, and wherein said contact portion is brought into contact withsaid first mirror holder, after said motor drives said driving membersuch that said second mirror holder is moved toward the third positionfrom a state in which said first mirror holder is positioned in thesecond position and said second mirror holder is positioned in thefourth position.
 6. The mirror drive device according to claim 5,wherein when said driving member moves said second mirror holder fromthe fourth position to the third position, said contact portion isbrought into contact with said first mirror holder to thereby move saidfirst mirror holder from the second position to the first position. 7.The mirror drive device according to claim 5, wherein when said firstmirror holder is moved from the second position to the first position,said contact portion enters a state in which said contact portion is notin contact with said first mirror holder before said first mirror holderreaches the first position.
 8. The mirror drive device according toclaim 1, wherein said first mirror holder is attached to a mirror box ina manner rotatable about a first rotation center, wherein said secondmirror holder is attached to said first mirror holder in a mannerrotatable about a second rotation center which is different from thefirst rotation center, wherein said driving member is attached to themirror box in a manner rotatable about a rotation center which isdifferent from the first rotation center and the second rotation center,and wherein the rotation center of said driving member is disposedradially inside radially inside a segment of a sector formed about thefirst rotation center by connecting the second rotation center locatedwhen said second mirror holder is in the third position and the secondrotation center located when said second mirror holder is in the fourthposition.
 9. The mirror drive device according to claim 8, wherein therotation center of said driving member is disposed in an area closer tothe second rotation center located when said second mirror holder is inthe third position than to the second rotation center located when saidsecond mirror holder is in the fourth position.
 10. A mirror drivedevice comprising: a first mirror holder that holds a first mirror andis configured to be movable between a first position in a photographingoptical path and a second position retracted from the photographingoptical path; a second mirror holder that holds a second mirror in astate rotatably attached to said first mirror holder and is configuredto be movable between a third position in the photographing optical pathand a fourth position retracted from the photographing optical path; amotor; a driving member configured to be driven by said motor to therebymove said second mirror holder between the third position and the fourthposition; and a control unit configured to control driving of saidmotor, wherein when said second mirror holder is moved from the thirdposition to the fourth position by said driving member, said firstmirror holder is positioned in the first position without being moveduntil said second mirror holder is brought into contact therewith, andafter said second mirror holder is brought into contact therewith, saidfirst mirror holder is moved to the second position together with saidsecond mirror holder, and wherein said control unit controls said motorto reduce speed thereof to thereby reduce speed of said second mirrorholder when said second mirror holder reaches a predetermined firstsetting position before said second mirror holder is brought intocontact with said first mirror holder, controls said motor to increasethe speed thereof to thereby increase the speed of said second mirrorholder after said second mirror holder is brought into contact with saidfirst mirror holder, and controls said motor to reduce the speed thereofto thereby reduce the speed of said second mirror holder when said firstmirror holder is moved toward the second position together with saidsecond mirror holder and reaches a predetermined second setting positionbefore reaching the second position.
 11. The mirror drive deviceaccording to claim 10, wherein the predetermined first setting positionis a position closer to a position where said second mirror holder isbrought into contact with said first mirror holder than to asubstantially midpoint position of a range through which said secondmirror holder is moved from the third position to the position wheresaid second mirror holder is brought into contact with said first mirrorholder.
 12. The mirror drive device according to claim 10, wherein thepredetermined second setting position is a position closer to the secondposition than to a midpoint position of a range through which said firstmirror holder is moved from the first position to the second position.13. A mirror drive device comprising: a first mirror holder that holds afirst mirror and is configured to be movable between a first position ina photographing optical path and a second position retracted from thephotographing optical path; a second mirror holder that holds a secondmirror in a state rotatably attached to said first mirror holder and isconfigured to be movable between a third position in the photographingoptical path and a fourth position retracted from the photographingoptical path; a motor; a driving member configured to be driven by saidmotor to thereby move said second mirror holder between the thirdposition and the fourth position; and a control unit configured tocontrol driving of said motor, wherein when said second mirror holder ismoved from the fourth position to the third position by said drivingmember, said first mirror holder is moved from the second positiontoward the first position together with said second mirror holder, andreaches the first, position, and after said first mirror holder reachesthe first position, said second mirror holder is moved toward the thirdposition, and reaches the third position, and wherein said control unitcontrols said motor to reduce speed thereof to thereby reduce the speedof said second mirror holder, when said first mirror holder is movedfrom the second position toward the first position together with saidsecond mirror holder and reaches a predetermined first setting positionbefore reaching the first position, controls said motor to increase thespeed thereof to thereby increase the speed of said second mirror holderafter said first mirror holder reaches the first position, and controlssaid motor to reduce the speed thereof to thereby reduce the speed ofsaid second mirror holder when said second mirror holder reaches apredetermined second setting position before reaching the thirdposition.
 14. The mirror drive device according to claim 13, wherein thepredetermined first setting position is a position closer to the firstposition than to a midpoint position of a range through which said firstmirror holder is moved from the second position to the first position.15. The mirror drive device according to claim 13, wherein thepredetermined second setting position is a position closer to the thirdposition than to a substantially midpoint position of a range throughwhich said second mirror holder is moved from a position where saidsecond mirror holder reaches the first position of said first mirrorholder together with said first mirror holder to the third position. 16.An image pickup apparatus comprising: a first mirror holder that holds afirst mirror and is configured to be movable between a first position ina photographing optical path and a second position retracted from thephotographing optical path; a second mirror holder that holds a secondmirror in a state rotatably attached to said first mirror holder and isconfigured to be movable between a third position in the photographingoptical path and a fourth position retracted from the photographingoptical path; a motor; and a driving member configured to be driven bysaid motor to thereby move said second mirror holder between the thirdposition and the fourth position, wherein said driving member moves saidsecond mirror holder from the third position to the fourth position,whereby said first mirror holder is moved from the first position to thesecond position.
 17. An image pickup apparatus comprising: a firstmirror holder that holds a first mirror and is configured to be movablebetween a first position in a photographing optical path and a secondposition retracted from the photographing optical path; a second mirrorholder that holds a second mirror in a state rotatably attached to saidfirst mirror holder and is configured to be movable between a thirdposition in the photographing optical path and a fourth positionretracted from the photographing optical path; a motor; a driving memberconfigured to be driven by said motor to thereby move said second mirrorholder between the third position and the fourth position; and a controlunit configured to control driving of said motor, wherein when saidsecond mirror holder is moved from the third position to the fourthposition by said driving member, said first mirror holder is positionedin the first position without being moved until said second mirrorholder is brought into contact therewith, and after said second mirrorholder is brought into contact therewith, said first mirror holder ismoved to the second position together with said second mirror holder,and wherein said control unit controls said motor to reduce speedthereof to thereby reduce speed of said second mirror holder when saidsecond mirror holder reaches a predetermined first setting positionbefore said second mirror holder is brought into contact with said firstmirror holder, controls said motor to increase the speed thereof tothereby increase the speed of said second mirror holder after saidsecond mirror holder is brought into contact with said first mirrorholder, and controls said motor to reduce the speed thereof to therebyreduce the speed of said second mirror holder when said first mirrorholder is moved toward the second position together with said secondmirror holder and reaches a predetermined second setting position beforereaching the second position.
 18. An image pickup apparatus comprising:a first mirror holder that holds a first mirror and is configured to bemovable between a first position in a photographing optical path and asecond position retracted from the photographing optical path; a secondmirror holder that holds a second mirror in a state rotatably attachedto said first mirror holder and is configured to be movable between athird position in the photographing optical path and a fourth positionretracted from the photographing optical path; a motor; a driving memberconfigured to be driven by said motor to thereby move said second mirrorholder between the third position and the fourth position; and a controlunit configured to control driving of said motor, wherein when saidsecond mirror holder is moved from the fourth position to the thirdposition by said driving member, said first mirror holder is moved fromthe second position toward the first position together with said secondmirror holder, and reaches the first position, and after said firstmirror holder reaches the first position, said second mirror holder ismoved toward the third position, and reaches the third position, andwherein said control unit controls said motor to reduce speed thereof tothereby reduce the speed of said second mirror holder, when said firstmirror holder is moved from the second position toward the firstposition together with said second mirror holder and reaches apredetermined first setting position before reaching the first position,controls said motor to increase the speed thereof to thereby increasethe speed of said second mirror holder after said first mirror holderreaches the first position, and controls said motor to reduce the speedthereof to thereby reduce the speed of said second mirror holder whensaid second mirror holder reaches a predetermined second settingposition before reaching the third position.